A SPACER WITH AN INDUCTION COIL OF AN INDUCTION HOB

Abstract

 The present invention relates to an induction hob comprising a cover plate with an inductor which is comprised among other things of an induction coil with spacers that enable air gaps between the induction coil and the cover plate, and in particular the invention refers to a spacer with said induction coil. It is provided according to the invention that the spacer (7) is formed by at least one groove (14) configured to accommodate a leg (13) of an element (12) for heat transfer.

Description

[0001] The present invention relates to an induction hob comprising an induction coil and spacers to enable an air gap between the induction coil and a cover plate, and in particular the invention refers to a spacer with said induction coil.

[0002] Care has to be taken of an appropriate thermal protection of induction coils in order for an induction hob to operate regularly and properly. Due to a need of an accurate control of heated container and, respectively, of medium in the container, an element for transfer heat to a temperature probe is used. The hot container heated up by means of said induction coil transfers part of the heat to the induction cover plate, whereby heat is transferred through the glass directly to the induction coil. The induction coil already warms up due to the operation thereof, however, with additional heat supply from the container with the medium to be heated onto the induction coil the latter can be overheated resulting in shorten lifespan and even a destruction. In order to prevent to high temperature to occur on the induction coil, the induction coil is provided with a probe which triggers power reduction of the induction coil when to high temperature is detected. Said element for transfer heat to the temperature probe must be reliably mounted between the thermal insulation and the electrical insulator under the glass in order to ensure an appropriate container temperature measurement.

[0003] Measurement of the temperature on the induction coil is carried out by means of a probe arranged inside induction coil. Wool insulation, or spacers for providing an air gap between the induction coil and a glass cover plate, or any other suitable thermal insulation material is used as an excess temperature protection. When the temperature is measured by means of the element for transferring heat to the temperature probe, wool insulation is used exclusively as a thermal protection which supposed to ensure an accurate arrangement of the element for heat transfer. In case that said element for heat transfer is displaced, heat transfer to the temperature probe can decrease resulting in irregular reading of temperature.

[0004] It is the object of the present invention to create a spacer with an induction coil of an induction hob, which remedies drawbacks of the known solutions.

[0005] The object as set forth is solved, according to the present invention, by features disclosed in the characterising part of claim 1. Detail of the invention is disclosed in respective sub-claims. In addition to providing an air gap between an induction coil and a glass cover plate, which enables an appropriate thermal protection, a spacer according to the invention also provides for a proper mounting of an element for transfer heat to a temperature probe. The spacer for heat transfer reliably and properly rests against both the induction coil and the glass cover plate with no possibility, whatsoever, to slip out of the position thereof. By means of reliable contact of the spacer and the glass cover plate there is ensured an accurate reading of the temperature of a container with medium to be heated and, as a result, a reliable contact of the element for heat transfer with the temperature probe.

[0006] The invention is further described in detail by way of non-limiting embodiment, and with a reference to the accompanying drawings, where

Fig. 1

shows a partial three-dimensional schematic view of an induction hob from below,

Fig. 2

shows a three-dimensional schematic side view of an inductor of the induction hob of Fig. 1.

[0007] Induction hob comprises a cover plate 1, preferably a glass or glass ceramic plate or a plate of other suitable material, having a cooking surface 2 for receiving a container with a medium to be heated, and at least one inductor 3 provided for heating said medium arranged under the cover plate 1 in each section under the cooking area. Said inductor 3 is via an electrical insulation means 4 in close connection with a lower surface 5 of the cover plate 1, so that the distance between the inductor 3 and the container with the medium to be heated is smallest possible.

[0008] Said inductor 3 comprises an induction coil 6 which is arranged, spaced from the cover plate 1 and, respectively, from said insulation means 4, on the underside of the cover plate 1. Said spacing provided by at least one spacer 7, preferably with a plurality of spacers 7, provides an appropriate air gap t between the induction coil 6 and the cover plate 1 and, respectively, said insulation means 4. The air gap t acts as a thermal insulator. Said spacers 7 are preferably equally spaced arranged over the circumference of the induction coil 6, particularly in a preferred way, that each spacer 7 extends approximately from the central region of the induction coil 6 towards the outside border thereof.

[0009] Directly under the induction coil 6 and, optionally, with an intermediate electrical insulation means is arranged a plurality of guiding elements for magnetic flux 8 preferably made on the basis of ferrites. The induction coil 6 is fed by energy via connectors 9. In the central region of the induction coil 6 is arranged a temperature probe 10 which sends via a line 11 information about temperature conditions in the inductor. However, the temperature probe 10 senses temperature only locally in a single point. In order to increase the temperature sensing surface it is provided for that an element 12 for heat transfer from the container with medium to be heated to the temperature probe 10 is associated with the temperature probe 10, preferably in the region between the insulation means 4 and the induction coil 6. Said element 12 for heat transfer is formed as a one-leg or a multi-leg element, for example, the legs 13 thereof are arranged in the plane of the induction coil 6. Each leg 13 of the element 12 for heat transfer cooperates with the spacer 7 which presses said leg 13 towards the cover plate 1 and, respectively, towards said insulation means 4.

[0010] The element 12 for heat transfer must rests precisely and reliably against the temperature probe 10 as well as against the cover plate 1 and, respectively, against said insulation means 4, thus, enabling reliable, repeatable and accurate reading of the temperature. To this extent, the element 12 for heat transfer must be unmoveably fixed in the inductor. Said fixed position of the element 12 for heat transfer is realized with said at least one spacer 7. To this extent, the spacer 7 is formed either at its surface which cooperates with the cover plate 1 and, respectively, with said insulation means 4, and/or its surface which cooperates with the induction coil 6, with at least one groove 14 provided to accommodate said leg 13 of the element 12 for heat transfer. Said groove 14 extends at least over a part of the length of the spacer 7. The depth of said groove 14 essentially equals the thickness of the leg 13.

[0011] The spacer 7 can be made either of resilient material or of stiff material. With the preferred embodiment is provided that the spacer 7 is made of synthetic resilient material, particularly preferably of temperature resistant resilient material such as of silicon rubber for example. The elasticity of the spacer 7 enables for the leg 13 of the element 12 for heat transfer located in the groove 14 to tightly rest against the cover plate 1 and, respectively, against the insulation means 4. When the spacer 7 is made of stiff material, resting of the element 12 for heat transfer against the lower surface 5 of the cover plate 1 and, respectively against the electrical insulation means 4 can be achieved by additional elastic means.

[0012] Furthermore, it is provided according to the present invention that said insulation means 4 is associated by means of an adhesion means with the lower surface 5 of the cover plate 1. Still further is provided that each spacer 7 is associated by means of an adhesion means and/or by means of a mechanical means with the insulation means 4 and/or with the induction coil 6.

Claims

1. A spacer with an induction coil of an induction hob, the latter comprising a cover plate with an inductor which is comprised of an induction coil and spacers for enabling an air gap between the induction coil and the cover plate, characterized in that a spacer (7) is formed, either at its surface that cooperates with a cover plate (1) and, respectively, with an electrical insulation means (4) by means of which an inductor (3) is tightly connected to the lower surface (5) of the cover plate (1), and/or at its surface that cooperates with an induction coil (6) which is arranged with a spacing (t) from the cover plate (1) and, respectively, from said insulation means (4), wherein a temperature probe (10) is arranged in the central region of the induction coil (6) to which is connected an element (12) for transfer of heat from a container with medium to be heated, wherein said element (12) for heat transfer is formed as an element comprising one or several legs (13), with at least one groove (14) configured to accommodate the leg (13) of the element (12) for heat transfer.

2. A spacer according to claim 1, characterized in that each leg (13) of the element (12) for heat transfer cooperates with the spacer (7) which presses said leg (13) against the cover plate (1) and, respectively, against said insulation means (4).

3. A spacer according to claim 1, characterized in that said groove extends (14) at least over a part of the length of the spacer (7), wherein the depth of said groove (14) essentially equals the thickness of said leg (13).

4. A spacer according to any of the preceding claim, characterized in that the spacer (7) is made of a temperature resistant material.

5. A spacer according to claim 4, characterized in that the spacer (7) is made of a temperature resistant resilient or stiff material.

6. A spacer according to claim s 4 and 5, characterized in that the elasticity of the spacer (7) provides for the leg (13) of the element (12) for heat transfer located in the groove (14) to be tightly pressed against the cover plate (1) and, respectively, against said insulation means (4).

7. A spacer according to any of the preceding claim, characterized in that each spacer (7) is associated by means of an adhesion means with the insulation means (4) and/or the induction coil (6).

8. Induction hob, comprising a cover plate with an inductor, which comprises an induction coil and spacers for providing air gaps between the induction coil and the cover plate, characterized in that it comprises at least one spacer according to any of claims 1 to 6.

Drawing